It is necessary to achieve a near perfect seal against release of vapors from a tank, particularly where the vapors may be toxic, odorous or flammable, while at the same time limiting pressure increases in the tank. That is, it is necessary to prevent the release of undesirable vapors to the atmosphere under static conditions as well as when the tank is being filled or is subjected to increasing pressure due to increasing temperatures. It is also necessary in some situations to prevent reducing the pressure in the tank to a low negative pressure which could cause the tank to collapse and it is desirable to prevent pulling atmospheric air into a tank for safety reasons which may occur when the tank is being emptied or the tank temperature falls. Conventional mechanical seals are subject to seepage and/or failure as they become worn, old, or are subject to chemical attack.
The present invention is directed to a liquid sealing apparatus for sealing vapors in a tank utilizing liquid seals.